The present invention generally relates to semiconductor fabrication methods and devices. More specifically, the present invention relates to forming multiple-bit electrical fuses (e-fuses) that can store multiple bits of data.
E-fuses are used in semiconductor-based integrated circuits (IC) for a variety of functions, including acting as a single-bit memory device that is permanent and cannot be erased. In many applications, groups of e-fuses are used to store unique ID numbers for each individual IC. A typical e-fuse has wide cathode and anode terminals while having a narrow “fusable” material between the two terminals. Each e-fuse can store one bit of data, being either a “0” or “1” depending on the programming.